releases/5.0.19/clk-sunxi-ng-nkmp-avoid-genmask-1-0.patch

   1 From 00437ac333d0524346793b5cdd834316f5bcfdf1 Mon Sep 17 00:00:00 2001
   2 From: Jernej Skrabec <jernej.skrabec@siol.net>
   3 Date: Tue, 2 Apr 2019 23:06:21 +0200
   4 Subject: clk: sunxi-ng: nkmp: Avoid GENMASK(-1, 0)
   5
   6 [ Upstream commit 2abc330c514fe56c570bb1a6318b054b06a4f72e ]
   7
   8 Sometimes one of the nkmp factors is unused. This means that one of the
   9 factors shift and width values are set to 0. Current nkmp clock code
  10 generates a mask for each factor with GENMASK(width + shift - 1, shift).
  11 For unused factor this translates to GENMASK(-1, 0). This code is
  12 further expanded by C preprocessor to final version:
  13 (((~0UL) - (1UL << (0)) + 1) & (~0UL >> (BITS_PER_LONG - 1 - (-1))))
  14 or a bit simplified:
  15 (~0UL & (~0UL >> BITS_PER_LONG))
  16
  17 It turns out that result of the second part (~0UL >> BITS_PER_LONG) is
  18 actually undefined by C standard, which clearly specifies:
  19
  20 "If the value of the right operand is negative or is greater than or
  21 equal to the width of the promoted left operand, the behavior is
  22 undefined."
  23
  24 Additionally, compiling kernel with aarch64-linux-gnu-gcc 8.3.0 gave
  25 different results whether literals or variables with same values as
  26 literals were used. GENMASK with literals -1 and 0 gives zero and with
  27 variables gives 0xFFFFFFFFFFFFFFF (~0UL). Because nkmp driver uses
  28 GENMASK with variables as parameter, expression calculates mask as ~0UL
  29 instead of 0. This has further consequences that LSB in register is
  30 always set to 1 (1 is neutral value for a factor and shift is 0).
  31
  32 For example, H6 pll-de clock is set to 600 MHz by sun4i-drm driver, but
  33 due to this bug ends up being 300 MHz. Additionally, 300 MHz seems to be
  34 too low because following warning can be found in dmesg:
  35
  36 [    1.752763] WARNING: CPU: 2 PID: 41 at drivers/clk/sunxi-ng/ccu_common.c:41 ccu_helper_wait_for_lock.part.0+0x6c/0x90
  37 [    1.763378] Modules linked in:
  38 [    1.766441] CPU: 2 PID: 41 Comm: kworker/2:1 Not tainted 5.1.0-rc2-next-20190401 #138
  39 [    1.774269] Hardware name: Pine H64 (DT)
  40 [    1.778200] Workqueue: events deferred_probe_work_func
  41 [    1.783341] pstate: 40000005 (nZcv daif -PAN -UAO)
  42 [    1.788135] pc : ccu_helper_wait_for_lock.part.0+0x6c/0x90
  43 [    1.793623] lr : ccu_helper_wait_for_lock.part.0+0x48/0x90
  44 [    1.799107] sp : ffff000010f93840
  45 [    1.802422] x29: ffff000010f93840 x28: 0000000000000000
  46 [    1.807735] x27: ffff800073ce9d80 x26: ffff000010afd1b8
  47 [    1.813049] x25: ffffffffffffffff x24: 00000000ffffffff
  48 [    1.818362] x23: 0000000000000001 x22: ffff000010abd5c8
  49 [    1.823675] x21: 0000000010000000 x20: 00000000685f367e
  50 [    1.828987] x19: 0000000000001801 x18: 0000000000000001
  51 [    1.834300] x17: 0000000000000001 x16: 0000000000000000
  52 [    1.839613] x15: 0000000000000000 x14: ffff000010789858
  53 [    1.844926] x13: 0000000000000000 x12: 0000000000000001
  54 [    1.850239] x11: 0000000000000000 x10: 0000000000000970
  55 [    1.855551] x9 : ffff000010f936c0 x8 : ffff800074cec0d0
  56 [    1.860864] x7 : 0000800067117000 x6 : 0000000115c30b41
  57 [    1.866177] x5 : 00ffffffffffffff x4 : 002c959300bfe500
  58 [    1.871490] x3 : 0000000000000018 x2 : 0000000029aaaaab
  59 [    1.876802] x1 : 00000000000002e6 x0 : 00000000686072bc
  60 [    1.882114] Call trace:
  61 [    1.884565]  ccu_helper_wait_for_lock.part.0+0x6c/0x90
  62 [    1.889705]  ccu_helper_wait_for_lock+0x10/0x20
  63 [    1.894236]  ccu_nkmp_set_rate+0x244/0x2a8
  64 [    1.898334]  clk_change_rate+0x144/0x290
  65 [    1.902258]  clk_core_set_rate_nolock+0x180/0x1b8
  66 [    1.906963]  clk_set_rate+0x34/0xa0
  67 [    1.910455]  sun8i_mixer_bind+0x484/0x558
  68 [    1.914466]  component_bind_all+0x10c/0x230
  69 [    1.918651]  sun4i_drv_bind+0xc4/0x1a0
  70 [    1.922401]  try_to_bring_up_master+0x164/0x1c0
  71 [    1.926932]  __component_add+0xa0/0x168
  72 [    1.930769]  component_add+0x10/0x18
  73 [    1.934346]  sun8i_dw_hdmi_probe+0x18/0x20
  74 [    1.938443]  platform_drv_probe+0x50/0xa0
  75 [    1.942455]  really_probe+0xcc/0x280
  76 [    1.946032]  driver_probe_device+0x54/0xe8
  77 [    1.950130]  __device_attach_driver+0x80/0xb8
  78 [    1.954488]  bus_for_each_drv+0x78/0xc8
  79 [    1.958326]  __device_attach+0xd4/0x130
  80 [    1.962163]  device_initial_probe+0x10/0x18
  81 [    1.966348]  bus_probe_device+0x90/0x98
  82 [    1.970185]  deferred_probe_work_func+0x6c/0xa0
  83 [    1.974720]  process_one_work+0x1e0/0x320
  84 [    1.978732]  worker_thread+0x228/0x428
  85 [    1.982484]  kthread+0x120/0x128
  86 [    1.985714]  ret_from_fork+0x10/0x18
  87 [    1.989290] ---[ end trace 9babd42e1ca4b84f ]---
  88
  89 This commit solves the issue by first checking value of the factor
  90 width. If it is equal to 0 (unused factor), mask is set to 0, otherwise
  91 GENMASK() macro is used as before.
  92
  93 Fixes: d897ef56faf9 ("clk: sunxi-ng: Mask nkmp factors when setting register")
  94 Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
  95 Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
  96 Signed-off-by: Sasha Levin <sashal@kernel.org>
  97 ---
  98  drivers/clk/sunxi-ng/ccu_nkmp.c | 18 +++++++++++++-----
  99  1 file changed, 13 insertions(+), 5 deletions(-)
 100
 101 diff --git a/drivers/clk/sunxi-ng/ccu_nkmp.c b/drivers/clk/sunxi-ng/ccu_nkmp.c
 102 index 9b49adb20d07c..69dfc6de1c4e6 100644
 103 --- a/drivers/clk/sunxi-ng/ccu_nkmp.c
 104 +++ b/drivers/clk/sunxi-ng/ccu_nkmp.c
 105 @@ -167,7 +167,7 @@ static int ccu_nkmp_set_rate(struct clk_hw *hw, unsigned long rate,
 106                            unsigned long parent_rate)
 107  {
 108         struct ccu_nkmp *nkmp = hw_to_ccu_nkmp(hw);
 109 -       u32 n_mask, k_mask, m_mask, p_mask;
 110 +       u32 n_mask = 0, k_mask = 0, m_mask = 0, p_mask = 0;
 111         struct _ccu_nkmp _nkmp;
 112         unsigned long flags;
 113         u32 reg;
 114 @@ -186,10 +186,18 @@ static int ccu_nkmp_set_rate(struct clk_hw *hw, unsigned long rate,
 115
 116         ccu_nkmp_find_best(parent_rate, rate, &_nkmp);
 117
 118 -       n_mask = GENMASK(nkmp->n.width + nkmp->n.shift - 1, nkmp->n.shift);
 119 -       k_mask = GENMASK(nkmp->k.width + nkmp->k.shift - 1, nkmp->k.shift);
 120 -       m_mask = GENMASK(nkmp->m.width + nkmp->m.shift - 1, nkmp->m.shift);
 121 -       p_mask = GENMASK(nkmp->p.width + nkmp->p.shift - 1, nkmp->p.shift);
 122 +       if (nkmp->n.width)
 123 +               n_mask = GENMASK(nkmp->n.width + nkmp->n.shift - 1,
 124 +                                nkmp->n.shift);
 125 +       if (nkmp->k.width)
 126 +               k_mask = GENMASK(nkmp->k.width + nkmp->k.shift - 1,
 127 +                                nkmp->k.shift);
 128 +       if (nkmp->m.width)
 129 +               m_mask = GENMASK(nkmp->m.width + nkmp->m.shift - 1,
 130 +                                nkmp->m.shift);
 131 +       if (nkmp->p.width)
 132 +               p_mask = GENMASK(nkmp->p.width + nkmp->p.shift - 1,
 133 +                                nkmp->p.shift);
 134
 135         spin_lock_irqsave(nkmp->common.lock, flags);
 136
 137 --
 138 2.20.1
 139